This invention relates generally to gas turbine engines, and more specifically to a turbofan engine assembly that includes a counter-rotating booster compressor.
At least some known turbofan engine assemblies include a fan assembly, a core gas turbine engine, and a low-pressure or power turbine. The core gas turbine engine includes at least one compressor, a combustor, and a high-pressure turbine that are coupled together in a serial flow relationship. Moreover, at least one known turbofan engine assembly includes a booster that is disposed between the fan assembly and the core gas turbine engine.
To improve the efficiency of the turbofan engine assembly, it is desirable to operate the fan assembly at a relatively low speed to improve fan efficiency and to operate the high-pressure turbine at a relatively high speed to improve the high-pressure turbine efficiency. However, operating the fan assembly at a relatively slow speed may be detrimental to the operation of a booster. As such, additional stages may be required on the booster to facilitate operating the booster at maximum efficiency, thus increasing the overall cost and design complexity of the turbofan engine.